Colposcopy and Treatment of Cervical Intraepithelial Neoplasia - RHO

An introduction to the anatomy of the uterine cervix
Ectropion
External os
Columnar
epithelium
Original SCJ
Original
squamous
epithelium
Metaplastic
squamous
epithelium
New SCJ
Columnar
epithelium
External os
a
b
c
d
Mature metaplastic
squamous epithelium
External os New SCJ External os Mature metaplastic
squamous epithelium
FIGURE 1.8: Location of squamocolumnar junction (SCJ)
(a) Original squamocolumnar junction (SCJ) in a young woman in the early reproductive age group. The SCJ is located far away from
the external os. Note the presence of everted columnar epithelium occupying a large portion of the ectocervix producing ectropion
(b) The new SCJ has moved much closer to the external os in a woman in her 30s. The SCJ is visible as a distinct white line after the
application of 5% acetic acid due to the presence of immature squamous metaplastic epithelium adjacent to the new SCJ
(c) The new SCJ is at the external os in a perimenopausal woman
(d) The new SCJ is not visible and has receded into the endocervix in a postmenopausal woman. Mature metaplastic squamous
epithelium occupies most of the ectocervix
reproductive period is referred to as the original
squamocolumnar junction, as this represents the
junction between the columnar epithelium and the
‘original’ squamous epithelium laid down during
embryogenesis and intrauterine life. During childhood
and perimenarche, the original squamocolumnar
junction is located at, or very close to, the external os
(Figure 1.7a). After puberty and during the
reproductive period, the female genital organs grow
under the influence of estrogen. Thus, the cervix swells
and enlarges and the endocervical canal elongates.
This leads to the eversion of the columnar epithelium
of the lower part of the endocervical canal on to the
ectocervix (Figure 1.7b). This condition is called
ectropion or ectopy, which is visible as a strikingly
reddish-looking ectocervix on visual inspection
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